Envelope detectors basically full wave rectify an input signal and filter the envelope of the resulting signal to provide an output signal which is representative of the envelope of the input signal. Envelope detectors are used in many applications including speech recognition systems which often rely upon the envelopes of several bandlimited sections of the speech input to provide a desired output. In discrete device technology, an envelope detector may be made by coupling an absolute value detector to a low pass filter. Such circuits typically are large and have diodes associated therewith which are very difficult to make in a standard MOS process. Others have implemented envelope detectors in switched capacitor technology as taught by P. E. Allen and E. Sanchez-Sinencio in a Texas A & M University text entitled Switched Capacitor Circuits (2nd Preliminary Edition May 1981). However, previous switched capacitor envelope detectors typically utilize at least one capacitor having a floating plate or electrode which is generally a source of error.